Inductance device



Dec. 11, 1951 J. GOUREVITCH INDUCTANCE DEVICE Filed Dec. 50, 1947 JACQUES GOUREWTCH Patented Dec. 11, 1951 INDUCTANCE DEVICE Jacques Gourevitch, Sevres, France, assignor to Wilhelm Franzos,

Paris, France Application December 30, 1947, Serial No. 794,669 In France June 13, 1947 9 Claims. 1

The invention is concerned with inductance devices and high frequency alternating-current transformers, band-pass-filters, high-pass-filters, low-pass-filters and the like devices constituted by at least two circuits coupled totally or partly by their leakage-flux.

In all such devices, the difficult problem is that of the coupling of the two circuits. In many cases it is necessary, or at least desirable, to modify or adjust the coupling-coefficient so as to thereby obtain a determined result. Up to now, the only way of acting upon the coupling was to displace one of the elements of the device with respect to the other, which usually requires a special disassembling and makes it difiicult to obtain the requisite accuracy.

The present invention has for its object to permit an easy, simple and accurate adjustment of the coupling without necessitating the least relative displacement of the axes of the two elements that constitute the device contemplated.

According to the invention, at least one of the two elements of the device is so constructed as to have an asymmetrical external magnetic field, whereby the coupling coefiicient between these two elements may be modified merely by rotating either one of said elements about its axis.

The invention refers to all devices constituted by at least two circuits coupled by their leakagefiux, whatever the nature of said devices and whatever the construction of the elements thereof. It relates more particularly to high frequency filters or transformers in which the elements of the device comprise cores and more particularly cores made of sub-divided or comminuted iron.

According to one feature of the invention, the outer magnetic field of at least one of the elements is made asymmetrical in a plane normal to the magnetic axis of the circuit, by the fact that the thickness of the lateral walls of its core varies along it periphery, whereby there is brought about, on one part, a concentration of the magnetic flux where said thickness is comparatively greater and, on the other part, a dispersion of the magnetic flux where said thickness is smaller, so that the lines of magnetic flux, instead of being in the form of circles concentric to mangnetic axis of the circuit, are excentric or substantially oval.

According to a further feature of the invention, a substantial portion of the lateral or peripheric wall of the core of at least one of the elements of the device is cut away so as to form a lateral aperture in this wall, while the remainder of this wall is reinforced so as to secure the desired concentration of the flux on this side of the core. This construction of the core constitutes a very important additional advantage in that it permits the lateral insertion of the inductance winding through said aperture into the core without having to dismount it. This arrangement allows for the use of cores made of two concentric parts and for the insertion of the winding between said parts through the lateral opening of the outer part by effecting merely a small axial displacement of the inner part.

According to yet a further feature of the invention, the bottom wall of the outer part or body of the core is provided with a central hole of relatively small diameter and adapted to be traversed by the fastening of the inductance bolt, while the top wall of said body is provided with a central opening of larger diameter and adapted to allow for this axial displacement of the central part of the core.

According to a still further feature of the invention, the bottom wall of the body of the core is provided with a downwardly projecting pin adapted to be engaged selectively into one of a corresponding circular series of holes, provided in the base or support of the inductance. Thus for the purpose of modifying the angular position of either inductance of the transformer with respect to the other, it suffices, first to loosen the fastening bolt and lift slightly this inductance, then to rotate this latter until its pin registers with the desired corresponding hole, and finally to tighten the bolt again.

Further features and advantages of the present invention will become apparent from the reading of the following description made in reference to the accompanying diagrammatic drawings in which:

Fig. 1 is a horizontal sectional view showing a device according to the invention, constituted by two inductances coupled by their leakageflux;

Fig. 2 is a horizontal sectional view showing a preferred embodiment of the orientable inductance of the device according to the invention;

Fig. 3 is an axial sectional view corresponding to Fig. 2;

Fig. 4 is an axial sectional view of a modification of the orientable inductance shown Figs. 2 and 3, and

Fig. 5 is a perspective view showing a filter or transformer according to the invention during the operation of angular adjustment of its orientable inductance.

Referring first to Fig. 1, there are shown two inductances having a magnetic core made of.

two concentric parts I, and respectively 2, 6. The lateral wall of the outer part I of one of these inductances is of variable thickness in order to create an asymmetrical external magnetic field, in accordance with the invention, whereas the lateral wall of the outer parts of the other inductance is of uniform thickness, as usually. 3, 3 designate the respective inductance windings mounted between the parts I, 5 and respectively 2, 6, while i designates the 'usual fastening bolt of the core I, 5.

The asymmetrical magnetic field lines of the core i, 5 are indicated by the reference numeral 4, while the reference numeral 4a indicates the concentric magnetic field lines of the core 2, 6. While in this embodiment of the device only one of the ,two inductances is asymmetrically designed according to the invention, it must be understood that the invention is not limited to a transformer or a filter in which only one of the two circuits is asymmetrical as above defined, but involves generally' all devices having asymmetrical circuits, as above defined, and constituted by a least two circuits coupled by their eakage flux, more particularly any device havng at least one such asymmetrical circuit and still more particularly a device having :two such asymmetrical circuits.

In'Fig. 2 there is shown a preferred form :of orientab'le inductance 'accordingto the invention. Herein, instead of being of variable thickness, a substantial portion of the annular wall of the outer-part i is cut away so as to form therein a lateral aperture 3 (see also Figs. 3, i and '5) wide enough to permit the lateral insertion of the inductance winding 3 therethrough into said outerpart I. The winding 3 is then secured into coaxial position by introducing axially into the outerpart i the inner part of the core, which is made of two superposed parts 5, 5a (Fig. 3) or 5, 5b (Fig. 4) which may be adjustable or 'fixed' with respect to each other. To this end, the bottom wall of the outer part or cage I is provided with a central hole of relatively small diameter H and adapted to be traversed by the fastening bolt 1, whereas the top wall thereof is provided with a central openin I la, coaxial with said hole H and through which two parts 5, eon-of the central part of the core may be introduced into the cage 1 so as to :center :and to immobilize the winding 3. In the example shown the said central part of the core is adjustable and comprises a fixed member '5 and a magnetic ring be adapted to be displaced along the fastening bolt 7. Such arrangement. is of the kind described in the French patent application filed byMM. J. Gourevitch and A. P. Metroz, January 29, 1947, for Improvements in Magnetic Cores. The realization of inductances accordin to the invention, whihc comprise a lateral aperture in the cage or outer part of the core for the introduction of "the inductance winding and an axial opening of said cage large enough for the introduction of the inner part of the core, lends itself particularly well 'to the use of adjustable cores of this kind. The invention aims particularly at the combination of an orientable inductance of the type described with an adjustable inner core in two parts as described in the aboveidentified application.

The centering ofthe lower inner part -5 of the core with respect to the outer part 3 thereof may be secured either by means of a cylindrical recess as shown in Fig. 3, or by means of a conical recess (Fig. 4), in which case this part 5 is provided with a conical appendage 50.

Obviously, any convenient means may be provided for orienting, i. e. modifying the angular position of the orientable inductance on its supporting structure. In Fig. 5 there is shown a simple mode of realization of these means, in which the cage I is provided with a downwardly projecting pin 9, whereas the base or support I2 is provided with a circular row of corresponding holes it. In order to modify the angular position of the cage I, all that is necessary is first to .loosen the nut I3 (Figs. 3 and i), to raise slightly the cage l and rotate the same until the pin 9 is engaged into the desired hole iii, and then to tighten the nut i3 again.

It will be understood that the invention is not limited to the particular device described and shown, as changes may be made therein without substantially departing from the spirit and scope of the invention, as defined in the accompanying claims.

I claim:

1. In a variable mutual inductance comprising at least two magnetic circuits constituted each by amagnetic core, a winding around said coreand a magnetic element surrounding said core and winding, said circuits being coupled by their leakage fluxes, a magnetic circuit of said type in which said magnetic element has an asymmetric shape in a plane perpendicular to the axis of the circuit to provide an asymmetric external magnetic field, and means for changing the angular position of said circuit about its axis so as to modify the coupling coemcient'between the circuits of said mutual inductance by the modification of the orientation of the leakage flux of the circuit comprising the asymmetric shaped magnetic element.

2. In a variable mutual inductancecomprising at least two magnetic circuits constituted each by a magnetic core, a winding around said core and a magnetic element surrounding said core and winding, said circuits-being coupled by their leakage fluxes, a magnetic circuit of said type in which said magnetic element has an irregular transversal section with respect to the axis of said circuit'to provide an asymmetric externalmagnetic field, and means for changing the angular position of said circuit about its axis so as to modify the coupling coefiicient between the circuits of sad mutual inductance by the modification of the orientation of the leakage flux of the circuit comprising the asymmetric shaped magnetic element.

3. In a variable mutual inductance comprising at least two magnetic circuits constitutedeach by 'a magnetic core, a Winding around said core anda magneto element surrounding said core and winding, said circuits being coupled by their leakage fluxes, a magnetic circuit of said type in which said magnetic element has a general cylindrical shape and is provided with a lateral opening de'terminingan asymmetric leakage fiux and permitting the insertion of the winding by a displacement in a plane perpendicular to the axis of the magnetic circuit, and means for changing the angular position of said circuit about its axis so as'to modify theccup'ling coeficient between the circuits of said mutual inductance.

4. In a-variable mutual inductance comprising at l ast two magnetic circuits, at least one of which being constituted by a cylindrical magnetic core, a winding around said core and a sur rounding magnetic element having the shape of a closed cylinder, a lateral opening in said magnetic element determining an asymmetric leakage flux and permitting the insertion of said Winding by a displacement in a plane perpendicular to the axis of the magnetic circuit, and an axial circular opening on the top wall of said magnetic element permitting the insertion of said magnetic core by an axial displacement after the insertion by lateral displacement of the winding.

5. In a variable mutual inductance comprising at least two magnetic circuits, at least one of which being constituted by a cylindrical magnetic core, a winding around said core and a surrounding magnetic element having the shape of a closed cylinder, a lateral opening in said magnetic element determining an asymmetrical leakage flux and permitting the insertion of said winding by a displacement in a plane perpendicu ar to the axis of the magnetic circuit, an axial circular opening on the top wall of said magnetic element permitting the insertion of said magnetic core by an axial displacement after the insertion by lateral displacement of the winding, and an axial bore in the bottom wall of said magnetic element for centering said core.

6. In a variable mutual inductance comprising at least two magnetic circuits, at least one of which being constituted by a cylindrical magnetic core, a winding around said core and a surrounding magnetic element having the shape of a closed cylinder, a lateral opening in said magnetic element determining an asymmetrical leakage flux and permitting the insertion of said winding by a displacement in a plane perpendicular to the axis of the magnetic circuit, an axial circular opening on the top wall of said magnetic element permitting the insertion of said magnetic core by an axial displacement after the insertion by lateral displacement of the winding, an axial bore in the bottom wall of said magnetic element for centering said core, and a flat cylindrical magnetic member of a diameter fitting in said axial circular opening and adapted to move axial y in said opening.

'7. In a variable mutual inductance comprising at least two magnetic circuits, at least one of which being constituted by a cylindrical magnetic core, a winding around said core and a surrounding magnetic element moulded in one piece from a finely divided magnetic powder and having the shape of a closed cylinder, and a lateral opening in said magnetic element determining an asymmetrical leakage flux and permitting the insertion of said winding by a displacement in a plane perpendicular to the axis of themagnetic circuit.

8. A variable mutual inductance device comprising a support, at least two magnetic core structures mounted on said support, at least one of said magnetic core structures comprising an inner core, a coil on said core and a coil enclosing member of magnetic material made in one piece, a lateral opening in said coil enclosing member permitting the insertion of said coil and providing an outer magnetic field asymmetric with reference to the magnetic axis in a plane perpendicular to said axis, an axial aperture in the top wall of said coil enclosing member permitting the insertion of said inner core, and means permitting to modify the angular position of said coil enclosing member.

9. A variable mutual inductance device com.- prising a support, at least two magnetic core structures, at least one of said magnetic core structures comprising an inner core, a coil on said core and a coil enclosing member of magnetic material made in one piece, a lateral'opening in said coil enclosing member permitting the insertion of said coil and providing an outer magnetic field asymmetric with reference to the magnetic axis in a plane perpendicular to said axis, an axial aperture in the top wall of said core enclosing member permitting the insertion of the inner core, a member adapted to move axially in said aperture for adjusting purposes, a recess formed in the bottom wall of said coil enclosing member for centring said core, axial bores in said core and bottom wall of the coil enclosing member permitting to insert a means for fastening said magnetic core structure to said support in a given position, and means for varying the angular position of said coil enclosing member with reference to the other magnetic core structure so as to modify the coupling coeflicient between said coil enclosing member and said other magnetic core structures.

JACQUES GOUREVITCH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,699,506 Faus Jan. 15, 1929 2,090,991 Wohlfarth Aug. 24, 1937 2,107,172 Agricola Feb. 1, 1938 2,137,392 Cobb Nov. 22, 1938 2,163,448 Otto June 20, 1939 2,416,159 Dahline Feb. 18, 1947 FOREIGN PATENTS Number Country Date 577,339 France Sept. 3, 1924 

